The temperature dependence of magnetic domain walls in ferromagnetic systems with strong exchange coupling and weak lattice anisotropy is studied assuming that the thermal influence results mainly from the temperature dependence of the magnetization. We obtain that in lattices with an uniaxial symmetry like Co the wall width increases with temperature, but stays finite up to the Curie temperature Tc. In contrary, for a cubic lattice like Fe the wall width diverges for T → Tc, if only the lattice anisotropy is taken into account. The shape of the domain walls is not conserved, since at Tc the wall is determined only by the lowest order of anisotropy. In addition, the temperature dependence of a domain wall width for a thin magnetic film is determined. Using a special symmetry, we obtain a diverging wall width at a temperature markedly lower than Tc. However, the consideration of additional domain wall modes should modify this result.